Formulations that combine sunscreen activity and insect repellency have been described previously. See, U.S. Pat. Nos. 3,186,912; 4,963,591; PCT Appl. No. WO94/00104; U.S. Pat. No. 4,756,905; Japanese Appl. No. 59-199602; U.S. Pat. Nos. 5,204,090; 5,346,922; 3,594,481; Japanese Appl. No. 5-92915; U.S. Pat. No. 3,918,612 and EP Patent Appl. No. 0492007. N,N-diethyl-m-toluamide (deet) is used for insect repellency in many of these formulations due to its effectiveness, persistent activity and low toxicity. Many currently available formulations employ either an organic chemical sunscreen, a combination of organic chemical sunscreens or a combination of an inorganic sunscreen, such as zinc oxide (ZnO) or titanium dioxide (TiO.sub.2), and organic chemical sunscreens to block ultraviolet (UV) radiation. Combinations of sunscreens often are necessary to achieve an effectively high skin protection factor (SPF) value.
Formulations containing combinations of deet and inorganic metal oxide powders such as TiO.sub.2 previously have been described. For example, U.S. Pat. No. 4,756,905 discloses an opaque material containing a combination of deet and TiO.sub.2 in which the metal oxides in the formulation were intended to act as pigments for camouflage. Japanese Patent No. 59-199602 discloses use of TiO.sub.2 as a complexing agent with deet to retard skin absorption of deet and extend its repellency. In both instances, the TiO.sub.2 present in the formulation could not act as a sunscreen agent because of its particle size, and because the amount of TiO.sub.2 was not sufficient to provide an effectively high SPF. The TiO.sub.2 described in these patents was a standard pigment grade form of TiO.sub.2, which is not desirable because it appears white against the skin.
It is an object of this invention to provide improved combination sunscreen/insect repellent formulations for application to the skin that avoid the shortcomings of the prior art, in particular, which do not contain organic chemical sunscreen agents.
It is a further object of this invention to provide stable formulations that utilize high levels of micronized ZnO or TiO.sub.2, or mixtures thereof, for sunscreen protection, in combination with deet as the insect repelling agent.